PROJECT SUMMARY Within invertebrate and vertebrate model organisms, such as C. elegans and mice, evidence strongly suggests that tissue-specific manipulations of stress response pathways can signal systemically and induce these pathways in distal tissues. Compartmental proteotoxic stress in one tissue can be communicated to distal tissues and induce genetic pathways of the endoplasmic reticulum unfolded protein response (UPRER). We have shown that both neuronal and glial overexpression of the UPRER transcription factor, XBP-1s, in C. elegans causes upregulation of the stress responsive UPRER in unconnected, peripheral tissue. While originating from a single tissue, these manipulations appear capable of propagating synchronous changes to age-related and stress resistance phenotypes across multiple tissues and organs. This cell non-autonomous response reinforces the idea that in a multi-cellular organism, the sensing of protein stress can be conveyed and responded systemically across the organism. However, the genetic requirements necessary for this signaling mechanism remain unknown. We hypothesize that glial XBP-1s induces a trans-tissue signaling mechanism to coordinate an organism-wide stress response, longer lifespan, and improved metabolic state. This grant proposal seeks to identify the genetic requirements for both signaling and sensing glial activation of the cell non-autonomous UPRER. From an unbiased mutagenesis screen used in Aim 1, we will identify potential mediators of the cell non-autonomous induction of the UPRER that will provide potential therapeutic targets for aging and metabolic disorders. Additionally, in Aim 2 we propose to characterize both cell-autonomous and cell non-autonomous activation of the UPRER to determine differences in the proteome and transcriptome of these seemingly distinct pathways of UPRER activation. These analyses will elucidate how a distal tissue can detect and respond to the glial signal deriving from UPRER activation, and potentially discover novel cellular signals or aberrations sensed by the UPRER machinery. This proposal addresses a gap in the field of cellular stress response by dissecting how these pathways are systemically activated and communicated. Additionally, this research will advance the emerging field of glial biology through exploration of the enigmatic molecular mechanisms and functional consequences of glial signaling. Moving forward, this research will provide a basis for further investigation into the genetic pathways of cell non-autonomous signaling that increase longevity and stress resistance in mammals. Answering the questions described in this proposal will have therapeutic implications not only for normal aging, but also age- onset diseases.